Fixed and rotary wing aircraft typical of the Douglas DC-6 and DC-4, Lockheed Martin P-2 Neptune, and P-3 Orion and other types of fixed and rotary wing aircraft, have in the past been extensively modified to undertake airborne firefighting operations. Typically modifications to the airframe are made to accommodate high volume water and foam retardant fluid reservoirs. These aircraft are referred to as air tankers, and their combined water and retardant delivery capacity, as well as the delivery dispersal pattern of the water on the ground, determine if the aircraft qualifies for one of several air tanker ratings, which are certified by the Interagency Air Tanker Board (IAB).
Among the many methodologies developed over years of forest fire fighting, is a constant flow retardant delivery tank system, which uses a pair of doors that open gradually to permit progressive release of the retardant mixture from within an air tanker's fluid reservoir. This constant flow water bombing methodology can counteract the forward motion of the aircraft at various speeds while maintaining an even, well grouped, user programmable, retardant dispersal pattern on the ground. One variant of such a system was disclosed by MacDonald and Neuwirth, in U.S. Pat. No. 4,936,389 which issued on Jun. 26, 1990, entitled Fluid Dispenser For An Aircraft. MacDonald discloses a system wherein a head sensor determines the level of retardant in the aircraft retardant tank and dynamically controls the aperture of the drop doors to counter aircraft forward velocity to achieve a consistent dispersal pattern. A similar constant flow system, which calculates the remaining amount of fluid within a tank relative to aircraft ground speed to achieve controlled retardant discharge is disclosed by Foy and Uglum in U.S. Pat. No. 5,320,185 which issued on Jun. 15, 1994 entitled Aircraft Fluid Drop System and also Foy and Uglum in U.S. Pat. No. 5,451,016, which issued on Sep. 19, 1995 which was also entitled Aircraft Fluid Drop System.
Another methodology used to achieve constant flow rates is disclosed by Trotter and Woods in U.S. Pat. No. 5,279,481 which issued on Jan. 18, 1994 entitled Airborne Liquid Spreading System. In the disclosed system the differential pressure across the drop doors between internal tank pressure and external ambient pressure is determined by a sensor which then relays signals to a controller that varies the aperture of the doors to maintain a constant flow rate during the drop sequence.
All the aforementioned constant flow methodologies have certain limitations and deficiencies. For example, each involve modifying the host aircraft to achieve installation. Furthermore, many of the systems referenced cannot typically undertake multiple drops from the same tank and fluid volume without returning to the tanker base for refilling.
Other systems have been conceived which require only minimal modification to the host aircraft, but such systems are generally incapable of achieving an optimal dispersal pattern conducive to IAB certification for suppressing large fires. Such a system was disclosed by Newton in U.S. Pat. No. 3,698,480 which issued on Oct. 17, 1972, entitled Dual Tank Airborne Fire Retardant Dispensing System. Newton describes a cargo aircraft with a portable dual tank dispersal system which disperses the retardant slurry using pressure stored in a high pressure vessel which uses bleed air from the engines to permit recharging of the system.
The system disclosed by Newton is similar to the Lockheed-Martin C-130 Modular Airborne Firefighting (MAFF) System, manufactured by the Aero Union Corporation of Chico Calif. The MAFF system is currently in use by the air National Guard on behalf of the U.S. Forest Service, and state government authorities. The MAFF system uses a pair of retardant ejection tubes which extend rearward and downward, over the trailing edge of the opened cargo ramp of the aircraft, and due to fluid ejection limitations and a dual discharge manifold configuration cannot achieve the desired optimal ground dispersal pattern typical of such systems. Furthermore, due to the installation methodology and configuration of the MAFF system which utilizes the rear ramp of the Lockheed Martin C-130 aircraft, substantial airframe corrosion results when the retardant is discharged and vortices carry peripheral retardant spray upward into the underside of the aircraft tail empennage. Further corrosion can also result when the MAFF system is being refilled as external retardant filling interfaces are inadequate, and overfill retardant can spill onto the cargo floor.
Despite the portability of MAFFS and other roll-on roll-off (Ro—Ro) aerial fire fighting concepts, such systems generally require opening a door or ramp at the rear of the aircraft in flight and thereby compromise aircraft pressurization. Such systems also limit aircraft operating altitudes and speed and affect handling characteristics, and can also create safety of flight concerns particularly in mountainous terrain. In some configurations the retardant discharge assembly must be deployed prior to flight in the operable position which dramatically increases drag, and again impairs aircraft handling characteristics, restricting flight altitudes to below ten thousand feet, resulting in slower transit speeds to the fire.
Most aerial firefighting systems do not have on-board dynamic mixing capabilities of the foam fire retardant chemicals and water, which must be premixed on the ground and thereby preclude dynamic configuration in flight of the retardant mixture. Richardson et al, in U.S. Pat. No. 4,172,499 issued on Oct. 30, 1979 entitled Powder And Water Mixing And Dropping System Onboard An Aircraft disclosed a dynamic, in-flight retardant chemical powder and water scooping system, which forms an integral part of a modified airframe structure. The system, however, forms part of a dedicated firefighting assembly permanently installed on the host aircraft, and does not permit the system operator to dynamically select the ratio of retardant to water mix.
Other foam chemical mixing systems for helicopter bucket type of firefighting systems are disclosed by Burchert, in U.S. Pat. No. 4,993,495, which issued on Feb. 19, 1991, entitled Apparatus For Applying Firefighting Chemicals, and in a similar system disclosed by Baker, in U.S. Pat. No. 5,385,208, which issued on Jan. 31, 1995, entitled Airborne Fire Suppressant Foam Delivery Apparatus. However, all of these systems involve modified airframes, or are helicopter based and hence are incapable of working in conjunction with a non-dedicated, Ro—Ro, high volume delivery system. Nor is a Ro—Ro fixed wing system disclosed that can carry and provide access to multiple chemicals, dyes or other powder or fluid agents in flight which could be dynamically injected in various ratios into the water reservoir based on situational requirements determined by the airtanker flight crew, or on-scene commander.
A common complaint among senior U.S. Air Force staff members and the U.S. General Accounting Office involves the diverse types, consisting of some twelve different variants, of dedicated C-130's used to fulfill unique missions. This diversity of airframe types results in a lack of fleet uniformity driving up maintenance costs, with no flexibility to undertake alternate missions. The U.S. Air Force has expressed a desire to create flexibility in fire-fighting equipment, to keep abreast of technical advances, and achieve more uniformity within its C-130 aircraft fleet. The U.S. Forest Service shares a similar perspective.
A discharge chute used to eject retardant material from an aircraft is disclosed by Hawkshaw in U.S. Pat. No. 4,671,472 issued on Jun. 9, 1987, entitled Fire Bombing and Fire Bombers. Hawkshaw disclosed the mounting and integration of an unpressurized fluid discharge chute which can form part of an existing drop tank assembly, but the system requires airframe modifications.
Other known firefighting systems use high pressure water drop or streams, particularly helicopter based systems. One such system is described by Eason in U.S. Pat. No. 3,897,829, issued on Aug. 5, 1975 entitled Airborne Fire Suppression Unit. Eason discloses a portable, articulated boom with an adjustable nozzle and water reservoir. A similar system for a modular container, and spray nozzle assembly was disclosed by Tomlinson in U.S. Pat. No. 4,090,567, which issued on May 23, 1978 entitled Fire Fighting Helicopter. However, both the Eason and Tomlinson patents describe systems which are primarily suited for lateral firefighting typical of high rise apartment buildings with limited water reservoirs, which require directed horizontal water streams, and are not capable of meeting IAB drop pattern dispersal criteria. Further, such systems cannot deliver a large volume of water as is typically required in major forest fires.
An improvement to these helicopter related firefighting problems is disclosed by Bisson, in U.S. Pat. No. 5,135,055 which issued on Aug. 4, 1992, entitled Ground And Airborne Fire Fighting System And Method Of Fighting High Rise Building Fires. Bisson discloses a stationary helicopter in hover, which is connected to a ground based pumping means and water supply, through a hose, which discharges the high pressure water through a water cannon mounted on the helicopter. Although the system disclosed by Bisson has multi-axis water stream vectoring capabilities, with variable flow rate, the helicopter is tethered to a fire hose and cannot be made portable, or independent from the water source thereby restricting the mobility of the helicopter.
Although several rotary and fixed wing, vertical discharge aerial firefighting systems disclose variable flow rate, or constant flow rate discharge means, none of them are adapted for use with Ro—Ro aircraft such as the Lockheed-Martin C-130 without modifying the airframe. For example, the Aero Union Corporation's Lockheed-Martin C-130-based Retardant Aerial Delivery System's (RADS) is only partially Ro—Ro, and requires extensive modification to the lower fuselage to create the opening for the tank assembly which is installed for firefighting and removed when the aircraft is required for cargo operations.
Herlik in U.S. Pat. No. 5,549,259, issued on Aug. 27, 1996, entitled Innovative Airtankers And Innovative Methods For Aerial Firefighting, discloses a system reportedly able to precisely drop measured amounts of liquid using an infra-red vision system, computerized aiming references and high capacity impellers mounted in the discharge tubes. A similar, although lesser capability is also disclosed by Denoize et.al. in U.S. Pat. No. 5,878,819 issued on Mar. 9, 1999 entitled Device For Assisting With The Extinguishing Of Fires By Water Bombing Aircraft which integrates a fire detection sensor with a GPS aircraft positioning system and a geographic information system linked to a computer based aircraft route, drop coordination, and egress planner. However, Denoize et.al. fail to disclose beneficial features, such as temporary, portable, modular, non-dedicated, Ro—Ro, pressurized fuselage mounting methodology for a fully integrated fire retardant delivery system including control interfaces, with global positioning system capability for precision delivery and ground asset location, with fire detection, targeting, and vegetative fuel characterization sensors, telemetry antennas, and/or computer processing systems, which are not affected by mechanical failure, or inoperability of the host aircraft.
In conjunction with the aerial delivery of retardant, current firefighting operations for non-dedicated, Ro—Ro aircraft (e.g., MAFFS) and modified aircraft (e.g., RADS) are hindered by a lack of on-board infra-red, hyperspectral, and other spectral sensors for spot fire detection, radiant and kinematic heat mapping, fire perimeter mapping, ground crew detection, vegetative fuel load characterization, retardant targeting, and retardant delivery assessment capabilities.
Further, in conjunction with the aerial delivery of heavy payloads of retardant, current airborne firefighting operations have on occasion proven to be dangerous for ground crews engaged in fighting fires, or civilian populations within the vicinity of aircraft water bombing operations.
Further, In order for several aircraft and ground crews to benefit from geo-referenced infra red detection data, and GPS targeting coordinates obtained by only one aircraft equipped with a sensor and data processing system, requires the integration of a low cost, universal on board tactical line-of-sight (LOS) and/or, over-the-horizon (OTH) imagery, data, transmission and display information system.
Accordingly, there is a continuing, unaddressed need for an improved firefighting apparatus capable of temporary use on various host aircraft and capable of effective water and/or retardant delivery from the air.
Additionally, there is a continuing, unaddressed need for a firefighting apparatus and system capable of common aircraft roll-on, roll-off, non-dedicated operation, without requiring airframe modifications.
Additionally, there is a continuing, unaddressed need for a firefighting apparatus and system capable of providing for pressurized fuselage based, Ro—Ro aerial fire fighting.
Additionally, there is a continuing, unaddressed need for a non-dedicated, Ro—Ro firefighting apparatus and system providing for constant flow discharge or operator-definable discharge from a pressurized fuselage.
Additionally, there is a continuing, unaddressed need for a firefighting apparatus and system, incorporating fire detection sensing and targeting capabilities, and/or a data/imagery telemetry system integrated into a single portable, pressurized, pallet assembly which can move seamlessly between aircraft without requiring airframe modifications.
Finally, there is a continuing, unaddressed need for a firefighting apparatus and system which does not require airframe modifications, does not restrict normal aircraft performance, does not decrease aircraft safety margins, does not cause airframe corrosion damage, and does not inhibit mission readiness by being dedicated to a single aircraft through airframe modification.